Variable Flow Evaporator; System Minimum Water Volume; Evaporator Flow Rate - Carrier Pro-Dialog Plus 30HZ Installation, Operation And Maintenance Instructions

5.4 - Variable flow evaporator

Variable evaporator flow can be used in standard chillers.
The chillers maintain a constant leaving water temperature
under all flow conditions. For this to happen, the minimum
flow rate must be higher than the minimum flow given in
the table of permissible flow rates and must not vary by
more than 10% per minute.
If the flow rate changes more rapidly, the system should
contain a minimum of 6.5 litres of water per kW instead of
3.25 l/kW.

5.5 - system minimum water volume

Whichever the system, the water loop minimum capacity is
given by the formula:
Capacity = Cap (kW) x N litres
application
Normal air conditioning
Process type cooling
Where Cap is the nominal system cooling capacity (kW) at
the nominal operating conditions of the installation.
This volume is necessary for stable operation and accurate
temperature control.
legend
1 30HZ/HZV 043
2 30HZ/HZV 052-065
3 30HZ/HZV 091
4 30HZ/HZV 101-121
5 30HZ/HZV 141-161
6 30HZ/HZV 195-225
7 30HZ/HZV 250-280
14
N
3.25
6.5
Evaporator pressure drop curves, standard units
It is often necessary to add a buffer water tank to the circuit
in order to achieve the required volume. The tank must
itself be internally baffled in order to ensure proper mixing
of the liquid (water or brine). Refer to the examples below.
NOTE: The compressor must not restart more than 6 times
in an hour.
Bad
Bad

5.6 - Evaporator flow rate

30hZ/hZV
043
052-065
091
101-121
141-161
195-280
Water flow rate l/s
Good
Good
Min. water flow rate, l/s
Closed loop
4.1
5.0
6.0
8.5
9.9
12.0